Update basic.rst
Update basic.rst

overload -> override
https://stackoverflow.com/questions/12893907/are-polymorphism-overloading-and-overriding-similar-concepts
bionoid/kivy,inclement/kivy,rnixx/kivy,akshayaurora/kivy,kivy/kivy,LogicalDash/kivy,KeyWeeUsr/kivy,LogicalDash/kivy,inclement/kivy,bionoid/kivy,bionoid/kivy,akshayaurora/kivy,matham/kivy,Cheaterman/kivy,matham/kivy,KeyWeeUsr/kivy,Cheaterman/kivy,Cheaterman/kivy,rnixx/kivy,akshayaurora/kivy,inclement/kivy,LogicalDash/kivy,matham/kivy,Cheaterman/kivy,LogicalDash/kivy,bionoid/kivy,matham/kivy,KeyWeeUsr/kivy,KeyWeeUsr/kivy,kivy/kivy,kivy/kivy,rnixx/kivy